JP2005044915A - Element and device for image pickup - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging technology for creating a picture of high quality with sensitivity exceeding two-folds without mixing colors by addition of pixels. <P>SOLUTION: CCD 303 has a horizontal transfer path 65 of quadriphase drive. A part of signal charges in a buffer area BE is transferred to the horizontal transfer path 65 by a closing operation of a gate 63, and the transferred signal charge is transferred to a forward direction by two pixels. The remaining signal charges in the buffer area BE are transferred to the horizontal transfer path 65 by the opening operation of the gate 63. Then, the two pixels in a color same as the signal charges which are already transferred are added. The pixels added in the horizontal transfer path 65 are returned in an opposite direction by the four pixels and the two pixels are added again. Thus, the signal charges accumulated in the four approximate pixels in the same color can be added. Consequently, the picture of high quality can be created by sensitivity exceeding two-folds without mixing the colors by pixel addition. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an interline type imaging device and an imaging apparatus, and more particularly to an imaging technique for performing pixel addition.
[0002]
[Prior art]
In a digital still camera (hereinafter referred to as “digital camera”), it is required to increase the number of pixels of a CCD (imaging device). Along with this, the sensitivity of CCD tends to decrease, but there is a strong demand for higher sensitivity.
[0003]
Regarding the demand for higher sensitivity, a gate is provided between the vertical transfer unit and the horizontal transfer unit of the CCD, and the signal charges accumulated in two pixels having the same color filter are added to each other. There has been proposed a technique for improving the sensitivity without doing so (see Non-Patent Document 1 as a similar technique).
[0004]
[Non-Patent Document 1]
“CX-PAL”, Sony Corporation, July 2003, Volume 57, p14
[0005]
[Problems to be solved by the invention]
However, in the above-described pixel addition technique, only two pixels of the same color are added, so it is difficult to improve sensitivity exceeding twice.
[0006]
The present invention has been made in view of the above problems, and an object of the present invention is to provide an imaging technique capable of generating a high-quality image with sensitivity exceeding twice without mixing colors by pixel addition.
[0007]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the invention of claim 1 is an interline type image pickup device having a pixel array in which pixels having color filters are arrayed, and (a) a signal accumulated in the pixel array. A vertical transfer unit that transfers charges; and (b) a horizontal transfer unit that transfers signal charges transferred from the vertical transfer unit. A first horizontal transfer path for transferring charge; and (b-2) a second horizontal transfer path capable of transferring the signal charge in the forward direction and the reverse direction by a predetermined driving method. The signal charges accumulated in a plurality of pixels of the same color having the same color filter are added by transferring the signal charges in the forward and reverse directions.
[0008]
According to a second aspect of the present invention, in the imaging device according to the first aspect of the invention, the first horizontal transfer path is disposed in the vicinity of one end of the vertical transfer unit, and the second horizontal transfer path is It is disposed near the other end of the vertical transfer unit.
[0009]
According to a third aspect of the present invention, in the image pickup device according to the first aspect of the invention, the first horizontal transfer path and the second horizontal transfer path are disposed in the vicinity of one end of the vertical transfer unit.
[0010]
According to a fourth aspect of the present invention, in the imaging device according to any one of the first to third aspects, the predetermined driving method is a three-phase driving method or a four-phase driving method.
[0011]
The invention of claim 5 is an image pickup apparatus having the image pickup device according to any one of claims 1 to 4, wherein the signal charges are forward and backward in the second horizontal transfer path. When performing live view display relating to a subject based on an image signal sequentially output from the image pickup device and an adding unit that adds signal charges accumulated in a plurality of pixels of the same color by transferring, or And control means for activating the adding means when performing moving image shooting of the subject based on the image signal.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
<Main components of digital camera>
1 to 3 are diagrams showing a schematic configuration of an external appearance of a digital camera 1 according to an embodiment of the present invention. 1 is a plan view of the digital camera 1, FIG. 2 is a cross-sectional view taken from the position II-II in FIG. 1, and FIG. 3 is a rear view of the digital camera 1.
[0013]
The digital camera 1 functions as an imaging device, and includes a camera body 2 that has a substantially rectangular parallelepiped shape, and a photographic lens 3 that is detachably attached to the camera body 2. As shown in FIG. 1, in the digital camera 1, a memory card 8 for recording a photographed image is detachably stored. The digital camera 1 uses a power source battery E, which connects four AA batteries E1 to E4 in series, as a drive source.
[0014]
As shown in FIG. 2, the photographing lens 3 that is a zoom lens includes a lens group 30. Here, a two-group zoom lens is shown as the photographing lens 3, and the lens group 30 is roughly classified into two lens groups 300 and 301. 2 and 3, each of the lens groups 300 and 301 is shown as a single lens for convenience of illustration. However, actually, each lens group 300, 301 is not limited to a single lens, and may be configured as an aggregate of a plurality of lenses.
[0015]
On the other hand, a motor M1 for driving the lens group 300 and a motor M2 for driving the lens group 301 are provided in the camera body 2. By driving the motors M1 and M2, the lens groups 300 and 301 move in the optical axis direction independently of each other, whereby the zoom magnification of the photographing lens 3 can be changed. Further, by driving the lens groups 300 and 301 using these motors M1 and M2, it is possible to change the in-focus state of the taking lens 3, that is, to perform a focusing operation.
[0016]
A color image sensor (hereinafter referred to as “CCD”) 303 is provided at an appropriate position behind the lens group 30 of the photographing lens 3. The color image sensor 303 is a single-plate color area sensor in which R (red), G (green), and B (blue) color filters are attached in a checkered pattern on the surface of each pixel of an area sensor composed of a CCD. Composed. The color image sensor (hereinafter, “CCD”) 303 has a number of pixels of 1600 × 1200, for example. The configuration of the CCD 303 will be described in detail later.
[0017]
A grip part G is provided on the front surface of the camera body 2 as shown in FIG. Further, as shown in FIG. 3, a shutter button 9 and an AF mode switch 91 are provided on the upper surface of the camera body 2. The shutter button 9 has a half-pressed state (this is called “S1 state”) used as a trigger for focus adjustment and the like and a full-pressed state (this is called “S2 state”) used as a trigger for recording shooting. It has a function to detect and discriminate. The AF mode switch 91 is a switch for setting an AF mode at the time of shooting, a moving image shooting mode, and the like.
[0018]
On the other hand, an electronic viewfinder (hereinafter “EVF”) 20 and a liquid crystal display (hereinafter “LCD”) 10 are provided on the back of the camera body 2. Unlike the optical viewfinder, the EVF 20 and the LCD 10 that perform live view display of the image signal from the CCD 303 in the shooting standby state serve as a viewfinder.
[0019]
Further, the LCD 10 can display a menu screen for setting a shooting mode, shooting conditions, and the like in the recording mode, and can reproduce and display a captured image recorded in the memory card 8 in the reproduction mode.
[0020]
The camera body 2 is provided with a power switch 14 on the left side of the back surface and a quadruple switch 15 on the right side of the back surface. The quadruple switch 15 has a circular operation button, and various operations can be performed by pressing buttons SU, SD, SL, and SR in four directions of up, down, left, and right in this operation button. For example, it functions as a switch for changing the item selected on the menu screen displayed on the LCD 10 or changing the frame to be reproduced selected on the index screen. In the recording mode, the left and right buttons SL and SR function as switches for changing the zoom magnification. Specifically, the zoom magnification is changed by changing the relative positional relationship between the two lens groups 300 and 301 by driving the motors M1 and M2. More specifically, when the right switch SR is pressed, the camera moves continuously to the wide side, and when the left switch SL is pressed, the camera moves continuously to the tele side.
[0021]
A switch group 16 such as an execution switch 31, a cancel switch 32, a menu display switch 33, and a mode switch 34 is provided below the quadruple switch 15. The execution switch 31 is a switch for confirming or executing the content selected on the menu screen. The cancel switch 32 is a switch for canceling the content selected on the menu screen. The menu display switch 33 is a switch for displaying a menu screen on the LCD 10 and switching the contents of the menu screen. The mode changeover switch 34 is a switch for switching between “photographing mode” and “reproduction mode”. This shooting mode is a mode for shooting still images and moving images, and the playback mode is a mode for playing back and displaying the shot images recorded on the memory card 8 on the LCD 10 or EVF 20. When the digital camera 1 is started up, the shooting mode is automatically selected, but each time the mode switch 34 is pressed after the start-up, the shooting mode and the playback mode are switched.
[0022]
Next, the internal configuration of the digital camera 1 will be described. FIG. 4 is a schematic block diagram showing the internal configuration of the digital camera 1.
[0023]
The taking lens 3 includes a lens group 300, 301 and a diaphragm 302 for adjusting the amount of transmitted light. In FIG. 4, for convenience of illustration, the diaphragm 302 is shown to be disposed on the rear side of the lens group 301, but the arrangement of the diaphragm 302 is not limited to this. For example, the diaphragm 302 may be provided inside the lens group 301 (or 300), or may be provided between both lens groups 300 and 301.
[0024]
The CCD 303 converts the light image of the subject formed by the photographing lens 3 from an image signal of R (red), G (green), and B (blue) color components (a signal sequence of pixel signals received by each pixel). Signal) is output after photoelectric conversion. The timing generator 214 generates various timing pulses in order to control the driving of the CCD 303.
[0025]
The exposure control in the digital camera 1 is performed by adjusting the exposure amount of the diaphragm 302 and the CCD 303, that is, the charge accumulation time corresponding to the shutter speed. If the appropriate shutter speed cannot be set when the subject brightness is low, the inappropriate exposure due to insufficient exposure is corrected by adjusting the level of the image signal output from the CCD 303. That is, when the brightness is low, exposure control is performed by combining the shutter speed and gain adjustment. The level adjustment of the image signal is performed in the gain adjustment of the AGC circuit in the signal processing circuit 121.
[0026]
The timing generator 214 generates a drive control signal for the CCD 303 based on the reference clock transmitted from the timing control circuit 202. The timing generator 214 generates a clock signal such as a timing signal for integration start / end (exposure start / end), a light reception signal read control signal (horizontal synchronization signal, vertical synchronization signal, transfer signal, etc.) of each pixel, and the like. Output to the CCD 303.
[0027]
The signal processing unit 120 performs predetermined analog signal processing and digital signal processing on the image signal output from the CCD 303. The signal processing of the image signal is performed for each light reception signal of each pixel constituting the image data. The signal processing unit 120 includes an analog signal processing circuit 121, an A / D conversion circuit 122, a black level correction circuit 123, a white balance (WB) circuit 124, a γ correction circuit 125, and an image memory 126.
[0028]
The analog signal processing circuit 121 performs analog signal processing. The analog signal processing circuit 121 mainly includes a CDS (correlated double sampling) circuit and an AGC (auto gain control) circuit, and reduces the sampling noise of the pixel signal output from the CCD 303 and the signal. Adjust the level. The gain control in the AGC circuit includes a case where a shortage of a captured image is compensated when an appropriate exposure cannot be obtained by the aperture value of the aperture 302 and the exposure time of the CCD 303.
[0029]
The A / D conversion circuit 122 converts a pixel signal (image signal) that is an analog signal output from the analog signal processing circuit 121 into pixel data (image data) that is a digital signal. The converted pixel data (image data) is temporarily stored in the image memory 126.
[0030]
The black level correction circuit 123 corrects the black level of the image signal A / D converted by the A / D conversion circuit 122 to a reference black level. The WB circuit 124 performs level conversion on image data of each RGB color component. The WB circuit 124 converts the level of the image data of each RGB color component using the level conversion table input from the overall control unit 150. Note that the conversion coefficient (characteristic gradient) of each color component in the level conversion table is set for each captured image by the overall control unit 150.
[0031]
The γ correction circuit 125 is a circuit that corrects the γ characteristic of image data, and corrects the level of each pixel data using a preset γ correction table.
[0032]
The image memory 126 is a memory that temporarily holds the image data output from the γ correction circuit 125. The image memory 126 has a storage capacity capable of storing image data for one frame. That is, the image memory 126 has a capacity for storing image data of 1600 × 1200 pixels corresponding to the number of pixels of the CCD 303, and each pixel data is stored at a corresponding pixel position.
[0033]
The light control circuit 304 controls the light emission amount of the built-in flash 5 in flash photography to a predetermined light emission amount set by the overall control unit 150. In flash photography, the reflected light of the flash light from the subject is received by the light control sensor 305 simultaneously with the start of exposure, and when the amount of received light reaches a predetermined light emission amount, a light emission stop signal is output from the light adjustment circuit 304, In response to the light emission stop signal, the light emission of the built-in flash 5 is forcibly stopped, whereby the light emission amount of the built-in flash 5 is controlled to a predetermined light emission amount.
[0034]
The lens control unit 130 controls driving of the lens groups 300 and 301 and the diaphragm 302 in the photographing lens 3. The lens control unit 130 includes a diaphragm control circuit 131 that controls a diaphragm value of the diaphragm 302, a zoom control circuit 132 that changes the zoom magnification (in other words, changes the angle of view) by driving the motors M1 and M2. And a focus control circuit 133 that performs focus control by driving the motors M1 and M2.
[0035]
The aperture control circuit 131 drives the aperture 302 based on the aperture value input from the overall control unit 150, and sets the aperture amount to the aperture value. The focus control circuit 133 controls the driving amounts of the motors M1 and M2 based on the AF control signal input from the overall control unit 150, and sets the lens groups 300 and 301 to the focal position. The zoom control circuit 132 drives the motors M1 and M2 to move the lens groups 300 and 301 based on a zoom control signal input from the overall control unit 150 in response to an input from the quad switch 15. As a result, the zoom state moves to the wide side or the tele side.
[0036]
The display unit 140 performs display on the LCD 10 and the EVF 20. In addition to the LCD 10 and the EVF 20, the display unit 140 includes an LCD VRAM 141 serving as a buffer memory for image data reproduced and displayed on the LCD 10, and an EVF VRAM 142 serving as a buffer memory for image data reproduced and displayed on the EVF 20. The LCD VRAM 14 has a storage capacity of image data corresponding to the number of pixels 640 × 480 of the LCD, and the EVFVRAM 142 has a storage capacity of image data corresponding to the number of pixels of the EVF 20 of 400 × 300.
[0037]
In the shooting standby state, each pixel data of an image (live view image) sequentially generated by the CCD 303 every 1/30 (seconds) is subjected to predetermined signal processing by the signal processing unit 120, and then the image is displayed. Temporarily stored in the memory 126. Then, the data is read out by the overall control unit 150, adjusted in data size, transferred to the LCDVRAM 141 and EVFVRAM 142, and displayed on the LCD 10 and EVF 20 as a live view image. As a result, the photographer can visually recognize the subject image. In the playback mode, the image read from the memory card 8 is subjected to predetermined signal processing by the overall control unit 150, then transferred to the LCD VRAM 141, and played back and displayed on the LCD 10.
[0038]
The operation unit 101 inputs operation information of operation members related to photographing and reproduction provided in the camera body unit 2 described above to the overall control unit 150. The operation information input from the operation unit 101 includes operation information of each operation member such as the shutter button 9, the power switch 14, the quad switch 15, and the switch group 16.
[0039]
The overall control unit 150 is composed of a microcomputer and centrally controls the photographing function and the reproduction function. A memory card 8 is connected to the overall control unit 150 via a card interface 103. A personal computer PC is externally connected via the communication interface 105.
[0040]
The overall control unit 150 includes a ROM 151 that stores a processing program for performing a number of specific processes in the photographing function and a reproduction function, and a control program for controlling driving of each member of the digital camera 1 described above, and a processing A RAM 152 is provided as a work area for performing various arithmetic operations according to the program and the control program. The program data recorded on the memory card 8 as a recording medium can be read out via the card interface 103 and stored in the ROM 151. Therefore, these processing program and control program can be installed in the digital camera 1 from the memory card 8. The processing program and the control program may be installed from the personal computer PC via the communication interface 105.
[0041]
Further, the overall control unit 150 calculates an AE evaluation value based on the image data sent from the image memory 126. That is, the overall control unit 150 measures the luminance value related to the subject as the AE evaluation value. The calculated AE evaluation value is sent to the aperture control circuit 131 and the timing control circuit 202 of the lens control unit 130.
[0042]
<Configuration and Operation of CCD 303>
FIG. 5 is a diagram for explaining the configuration of the CCD 303.
[0043]
The CCD 303 is configured as an interline transfer type all-pixel readout method (progressive type) solid-state imaging device. The CCD 303 also receives a pixel array Mt in which photoelectric conversion units (pixels) 61 (61R, 61Gr, 61Gb, 61B) that perform photoelectric conversion upon receiving reflected light from a subject, and signal charges accumulated in the pixel array Mt. Has a vertical transfer unit 60a and a horizontal transfer unit 60b.
[0044]
The photoelectric conversion unit 61 includes a pixel 61R having a red (R) color filter, pixels 61Gr and 61Gb having a green (G) color filter, and a pixel 61B having a blue (B) color filter. being classified. The pixel array Mt has a color filter array in which these three primary color filters are arrayed by, for example, the Bayer method.
[0045]
The vertical transfer unit 60 a has a plurality of vertical transfer paths 62. Between the vertical transfer unit 60a and the second horizontal transfer path 65 (described later), one gate 63 is provided for each of the two vertical transfer paths 62. The gate 63 is a part for selectively transferring the charges vertically transferred by the vertical transfer unit 60a to the horizontal transfer unit 60b.
[0046]
The horizontal transfer unit 60 b includes a first horizontal transfer path 64 and a second horizontal transfer path 65 disposed in the vicinity of one end of the vertical transfer unit 62. That is, the second horizontal transfer path 65 is disposed in the vicinity of one end of the vertical transfer unit 60 a, and the first horizontal transfer path 64 is disposed in the vicinity of the second horizontal transfer path 65. A gate 67 having a length equivalent to that of the first and second horizontal transfer paths 64 and 65 is provided between the first horizontal transfer path 64 and the second horizontal transfer path 65.
[0047]
The second horizontal transfer path 65 is a transfer path that transfers charges by a four-phase drive method, and can transfer charges in the forward direction (direction toward the output amplifier 66) and can transfer charges in the opposite direction. is there. On the other hand, the first horizontal transfer path 64 is a transfer path for transferring signal charges by the two-phase driving method, and transfers the signal charges transferred from the second horizontal transfer path 65 to the output amplifier 66. Therefore, in the first horizontal transfer path 64, charges can be transferred at a relatively high speed in the forward direction, but transfer in the reverse direction is impossible.
[0048]
The gate 63 selectively transfers a plurality of signal charges related to each pixel line in the horizontal direction transferred from the pixel array Mt to the vertical transfer path 62 to the second horizontal transfer path 65.
[0049]
The CCD 303 having the above configuration can improve the sensitivity by pixel addition. The operation of pixel addition will be described below.
[0050]
6 to 18 are diagrams for explaining the pixel addition operation in the CCD 303. In FIGS. 6 to 18, subscripts 11 to 69 indicating positional relationships are attached to R, Gr, Gb, and B in order to clarify which pixel generated the charge.
[0051]
First, as shown in FIG. 6, the charge signals Gr11, R11,..., Gr19, R19 are transferred by the vertical transfer path 62 to the buffer area BE in the vicinity of the second horizontal transfer path 65 (gate 65).
[0052]
7, when the gate 63 is closed, some of the charge signals Gr12, R12, Gr14, R14,... In the buffer area BE are transferred to the second horizontal transfer path 65.
[0053]
Next, the charge signal on the second horizontal transfer path 65 is moved by two pixels to the left (forward direction) on the paper surface, and the gate 63 is opened to transfer the remaining pixel signals in the buffer area BE to the second. Transfer to the horizontal transfer path 65 (FIG. 8). Thereby, for example, the pixel signals Gr11 and Gr12 and the pixel signals R11 and R12 are added in the second horizontal transfer path 65.
[0054]
Next, the gate 63 is closed, and a part of the pixel signals in the buffer area BE is transferred to the blank portion of the second horizontal transfer path 65 shown in FIG. As a result, as shown in FIG. 9, the pixel signals B12, Gb12, B14, Gb14, etc. are transferred to the second horizontal transfer path 65.
[0055]
Next, as shown in FIG. 10, the charge signal on the second horizontal transfer path 65 is moved in the forward direction by two pixels.
[0056]
Next, the gate 63 is opened, and the remaining pixel signals in the buffer area BE are transferred to the second horizontal transfer path 65 (FIG. 11). Thereby, for example, the pixel signals B11 and B12 and the pixel signals Gb11 and Gb12 are added in the second horizontal transfer path 65.
[0057]
Next, as shown in FIG. 12, the charge signal on the second horizontal transfer path 65 is moved by four pixels in the right direction, that is, in the reverse direction.
[0058]
Next, some of the gates 63 are opened, and some of the pixel signals in the buffer area BE are transferred to the second horizontal transfer path 65 (FIG. 13). Thereby, in the second horizontal transfer path 65, for example, the pixel signal Gr22 is added to the pixel signals Gr11 and Gr12, or the pixel signal R22 is added to the pixel signals R11 and R12.
[0059]
Next, as shown in FIG. 14, the charge signal on the second horizontal transfer path 65 is moved in the forward direction by two pixels.
[0060]
Next, a part of the gates 63 is opened, and the remaining pixel signals in the buffer area BE are transferred to the second horizontal transfer path 65 (FIG. 15). Thereby, in the second horizontal transfer path 65, for example, the pixel signal Gr21 is added to the pixel signals Gr11, Gr12, and Gr22, or the pixel signal R21 is added to the pixel signals R11, R12, and R22.
[0061]
Next, a part of the gates 63 is opened, and a part of the pixel signals in the buffer area BE is transferred to the second horizontal transfer path 65 (FIG. 16). Thereby, in the second horizontal transfer path 65, for example, the pixel signal B22 is added to the pixel signals B11 and B12, or the pixel signal Gb22 is added to the pixel signals Gb11 and Gb12.
[0062]
Next, as shown in FIG. 17, the charge signal on the second horizontal transfer path 65 is moved in the forward direction by two pixels.
[0063]
Next, a part of the gates 63 is opened, and the remaining pixel signals in the buffer area BE are transferred to the second horizontal transfer path 65 (FIG. 18). Thereby, in the second horizontal transfer path 65, for example, the pixel signal B21 is added to the pixel signals B11, B12, and B22, or the pixel signal Gb21 is added to the pixel signals Gb11, Gb12, and Gb22.
[0064]
Finally, as shown in FIG. 18, each signal charge added on the second horizontal transfer path 65 is transferred to the first horizontal transfer path 64 by opening the gate 67, and then fast forward in the forward direction by the first horizontal transfer path 64. Move with. As a result, an output of the CCD obtained by adding four pixels is obtained.
[0065]
As described above, by transferring the signal charges in the forward and backward directions in the second horizontal transfer path 64, the signal charges accumulated in a plurality of pixels of the same color having the same color filter are added for four pixels. FIG. 19 shows the arrangement of the pixels added at this time. FIG. 19 is a diagram showing the pixel arrangement Mt of the CCD 303. Four closest pixels of the same color such as R pixels indicated by a thick frame in the circle C1 and R pixels indicated by a broken line in the circle C2 are added. The Rukoto. In the same way, for the Gr (Gb) pixel and the B pixel, four adjacent pixels of the same color are added.
[0066]
Note that the CCD 303 is configured to be able to perform pixel thinning readout. When this pixel thinning readout is performed, as shown in FIG. 20, the R, Gr, Gb, and B pixels indicated by the thick frames in the circles D1, D2, and D3 are thinned and read out. By this thinning readout, the total number of pixels of the CCD 303 is reduced to ¼ and output.
[0067]
<Operation of Digital Camera 1>
FIG. 21 is a flow chart for explaining the basic operation of the digital camera 1. This operation is mainly a moving image shooting or still image shooting operation in the shooting mode, and is executed by the overall control unit 150.
[0068]
First, the photographer turns on the power switch 14 to activate the image pickup apparatus 1, and operates the mode switch 34 to set the photographing mode (step ST1).
[0069]
In step ST2, it is determined whether or not moving image shooting is set. In this case, the AF mode switch 91 determines whether the moving image shooting mode is set. If the moving image shooting is set, the process proceeds to step ST3. If the moving image shooting is not set, the process proceeds to step ST10.
[0070]
In step ST3, based on the image signals sequentially output from the CCD 303, moving image shooting relating to the subject is started.
[0071]
In step ST4, the overall control unit 150 measures the subject brightness, that is, the AE evaluation value.
[0072]
In step ST5, it is determined whether the subject brightness measured in step ST4 is equal to or greater than a predetermined value α. If the subject brightness is equal to or higher than the predetermined value α, the process proceeds to step ST6. If the subject brightness is smaller than the predetermined value α, the process proceeds to step ST7.
[0073]
In step ST6, pixel thinning readout is performed in the CCD 303. Here, for example, as shown in FIG. 20, the image is output from the CCD 303 with the aspect ratio thinned out to a line ratio of 1/2.
[0074]
In step ST7, pixel addition reading is performed in the CCD 303. That is, when the AE evaluation value measured by the overall control unit 150 is equal to or less than the predetermined value α, the above-described addition means for performing the 4-pixel addition is activated. Here, as described with reference to FIGS. 6 to 18, the CCD 303 outputs an image signal in which signal charges of four pixels of the same color are combined as shown in FIG.
[0075]
In step ST8, a moving image is recorded. In this case, a moving image based on image signals sequentially output from the CCD 303 is stored in the memory card 8.
[0076]
In step ST9, it is determined whether or not to finish moving image shooting. Here, it is determined whether the setting of the moving image shooting mode has been canceled by the AF mode switch 91. If the moving image shooting is not terminated, the process returns to step ST4.
[0077]
In step ST10, live view display for the subject is started based on image signals sequentially output from the CCD 303.
[0078]
In steps ST11 to ST14, operations similar to those in steps ST4 to ST7 are performed.
[0079]
In step ST15, it is determined whether or not the photographer has fully pressed the shutter button 9 (S2). If the shutter button 9 is fully pressed, the process proceeds to step ST16. If the shutter button 9 is not fully pressed, the process proceeds to step ST17.
[0080]
In step ST16, a still image is recorded. In this case, a still image based on the image signal output from the CCD 303 is stored in the memory card 8.
[0081]
In step ST17, it is determined whether or not to end still image shooting. Here, for example, it is determined whether or not the shooting mode has been switched to the playback mode by the mode switch 34. Here, when still does not end photographing, the process returns to step ST11.
[0082]
By the operation of the digital camera 1 described above, the charge is transferred in the reverse direction in the second horizontal transfer path 65, and the signal charge is added for every four neighboring pixels of the same color. High quality images can be generated with sensitivity exceeding.
[0083]
Further, when live view display or moving image shooting is performed, the number of necessary pixels is smaller than the total number of pixels of the CCD 2 because the adding means for performing pixel addition in the second horizontal transfer path 65 is activated. In live view display and moving image shooting, pixel addition can be easily performed, and an image signal with a good S / N ratio can be generated even if the subject brightness decreases.
[0084]
Further, since the first horizontal transfer path 64 of two-phase driving is disposed in the vicinity of the second horizontal transfer path 65, the signal charge obtained by pixel addition can be transferred to the output amplifier 66 at high speed. That is, when the pixel addition is completed, the signal charge is field-shifted to the first horizontal transfer path 64 and the second horizontal transfer path 65 is emptied, so that the second charge is transferred in parallel with the transfer of the signal charge by the first horizontal transfer path 64. Pixel addition can be performed in the horizontal transfer path 65. By such parallel processing, pixel addition and charge transfer to the output amplifier 65 can be performed at high speed as a total.
[0085]
In the CCD 303, it is not essential to provide the buffer area BE, and the buffer area BE may not be provided.
[0086]
Further, regarding the CCD, the configuration of the CCD 303 shown in FIG. 5 is not essential, and the configuration of the CCD 303A described below may be used.
[0087]
FIG. 22 is a diagram for explaining the configuration of the CCD 303A.
[0088]
The CCD 303A has a configuration similar to that of the CCD 303, but mainly the positions of the gate 63 and the second horizontal transfer path 65 are different.
[0089]
The CCD 303A is provided with a first horizontal transfer path 64 and a second horizontal transfer path 65 on both sides of the photoelectric conversion unit 61 and the vertical transfer path 62. That is, the first horizontal transfer path 64 is disposed in the vicinity of one end of both ends of the vertical transfer unit 62, and the second horizontal transfer path 65 is disposed in the vicinity of the other end of the vertical transfer unit 62. Further, since the second horizontal transfer path 65 is provided at a position away from the first horizontal transfer path 64, in addition to the output amplifier 66a for outputting the signal charges on the first horizontal transfer path 64, the second horizontal transfer path is provided. An output amplifier 66b for outputting signal charges on the path 65 is added, and the gate 67 of the CCD 303 is omitted.
[0090]
In the CCD 303A configured as described above, similarly to the operation of the CCD 303, pixel addition is performed by the second horizontal transfer path 65 capable of transferring charges in the forward direction and the reverse direction, and an image signal is output from the output amplifier 66b. It will be. When pixel addition is not performed, an image signal is output at high speed from the output amplifier 66b through the first horizontal transfer path 64 driven in two phases. As a result, when the subject brightness is low during movie shooting or live view shooting, the above pixel addition is performed to obtain a high-quality image with sensitivity improved by more than twice without color mixing. it can.
[0091]
<Modification>
For the second horizontal transfer path in the above embodiment, it is not essential to transfer the signal charge by the four-phase driving method, and it can be transferred in the forward direction and the reverse direction such as the three-phase driving method and the driving method of five phases or more. You may make it transfer by a system.
[0092]
For pixel addition in the above embodiment, it is not essential to perform 4-pixel addition in the CCD 303 (303A), and addition of 6 or more pixels may be performed. For example, from the state in which four pixels are added as shown in FIG. 18, if pixel addition is performed by returning the signal charge by four pixels in the reverse direction in the second horizontal transfer path 65, six pixels can be added. Since the six pixels added in this case are pixels of the same color that are close to each other, a high-quality image can be generated with six times the sensitivity.
[0093]
For the measurement of the subject brightness in the above embodiment, it is not essential to perform the measurement by the overall control unit 150 based on the acquired image data and measure by software, and the measurement is performed by the light control sensor 305 or the like. Also good.
[0094]
The specific embodiment described above includes an invention having the following configuration.
[0095]
(1) The image pickup device is a progressive type image pickup device.
[0096]
Thereby, pixel addition can be easily performed.
[0097]
(2) The image pickup device characterized in that the pixel array has a color filter array in which three primary color filters are arrayed in a Bayer manner.
[0098]
Thus, appropriate pixel addition can be performed even in a Bayer array.
[0099]
(3) The vertical transfer section has a plurality of vertical transfer paths, and between the vertical transfer section and the second horizontal transfer path, at least two vertical transfer paths are provided with a gate at a ratio of 1. An imaging device as a feature.
[0100]
Thereby, pixel addition can be performed easily and appropriately.
[0101]
(4) The image pickup device, wherein the second horizontal transfer path is disposed in the vicinity of one end of the vertical transfer unit, and the first horizontal transfer path is disposed in the vicinity of the second horizontal transfer path.
[0102]
Thereby, pixel addition processing can be performed quickly.
[0103]
(5) An adding means for adding the signal charges accumulated in pixels of the same color by transferring the signal charges in the forward and reverse directions in the second horizontal transfer path, and a photometric means for measuring the luminance value of the subject. An imaging apparatus comprising: means for activating the addition means when the luminance value measured by the photometry means is equal to or less than a predetermined value.
[0104]
As a result, the S / N ratio of the image can be appropriately improved even when the subject is dark.
[0105]
【The invention's effect】
As described above, according to the first to fifth aspects of the present invention, the signal charge is forward and backward in the second horizontal transfer path capable of transferring the signal charge in the forward and reverse directions by a predetermined driving method. , The signal charges accumulated in a plurality of pixels of the same color having the same color filter are added. As a result, it is possible to obtain a high-quality image with sensitivity improved by more than twice without mixing colors by pixel addition.
[0106]
In particular, in the second aspect of the present invention, the first horizontal transfer path is disposed in the vicinity of one end of the vertical transfer unit, and the second horizontal transfer path is disposed in the vicinity of the other end of the vertical transfer unit. A high-quality image can be appropriately acquired by the addition.
[0107]
In the invention of claim 3, since the first horizontal transfer path and the second horizontal transfer path are arranged near one end of the vertical transfer unit, a high-quality image can be quickly acquired by pixel addition.
[0108]
In the invention of claim 4, since the predetermined driving method is the three-phase driving method or the four-phase driving method, the signal charges can be easily transferred in the reverse direction in the second horizontal transfer unit.
[0109]
In the invention of claim 5, when performing live view display relating to the subject based on the image signal sequentially output from the image sensor, or when performing moving image shooting relating to the subject based on the image signal, the adding means is provided. Since it is activated, pixel addition can be easily performed at the time of live view shooting and moving image shooting where the required number of pixels is smaller than the total number of pixels of the image sensor.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic configuration of an external appearance of a digital camera 1 according to an embodiment of the present invention.
FIG. 2 is a diagram showing a schematic configuration of the external appearance of the digital camera 1;
FIG. 3 is a diagram illustrating a schematic configuration of an external appearance of the digital camera 1;
4 is a schematic block diagram showing an internal configuration of the digital camera 1. FIG.
FIG. 5 is a diagram for explaining a configuration of a CCD 303;
6 is a diagram for explaining an operation of pixel addition in the CCD 303. FIG.
FIG. 7 is a diagram for explaining an operation of pixel addition in the CCD 303;
FIG. 8 is a diagram for explaining an operation of pixel addition in the CCD 303;
FIG. 9 is a diagram for explaining the pixel addition operation in the CCD 303;
FIG. 10 is a diagram for explaining the pixel addition operation in the CCD 303;
FIG. 11 is a diagram for explaining an operation of pixel addition in the CCD 303;
12 is a diagram for explaining an operation of pixel addition in the CCD 303. FIG.
13 is a diagram for explaining the pixel addition operation in the CCD 303. FIG.
FIG. 14 is a diagram for explaining an operation of pixel addition in the CCD 303;
FIG. 15 is a diagram for explaining an operation of pixel addition in the CCD 303;
FIG. 16 is a diagram for explaining the pixel addition operation in the CCD 303;
FIG. 17 is a diagram for explaining the pixel addition operation in the CCD 303;
FIG. 18 is a diagram for explaining an operation of pixel addition in the CCD 303;
FIG. 19 is a diagram for explaining an arrangement of pixels to be added by four pixels.
FIG. 20 is a diagram for explaining an arrangement of pixels read by thinning readout.
FIG. 21 is a flowchart explaining the basic operation of the digital camera 1;
FIG. 22 is a diagram for explaining a configuration of a CCD 303A.
[Explanation of symbols]
1 Digital camera
61 Photoelectric converter
62 Vertical transfer path
63 Gate
64 First horizontal transfer path
65 Second horizontal transfer path
66 Output amplifier
150 Overall control unit
303, 303A CCD
BE buffer area
Mt pixel array

Claims (5)

An interline type imaging device having a pixel array in which each pixel having a color filter is arrayed,
(A) a vertical transfer unit that transfers signal charges accumulated in the pixel array;
(B) a horizontal transfer unit that transfers the signal charges transferred from the vertical transfer unit;
With
The horizontal transfer unit
(B-1) a first horizontal transfer path for transferring the signal charge by a two-phase driving method;
(B-2) a second horizontal transfer path capable of transferring the signal charge in the forward direction and the reverse direction by a predetermined driving method;
Have
The signal charges accumulated in a plurality of pixels of the same color having the same color filter are added by transferring the signal charges in the forward direction and the reverse direction in the second horizontal transfer path. element. The imaging device according to claim 1,
The first horizontal transfer path is disposed near one end of the vertical transfer unit,
The image pickup device, wherein the second horizontal transfer path is disposed in the vicinity of the other end of the vertical transfer unit. The imaging device according to claim 1,
The image sensor according to claim 1, wherein the first horizontal transfer path and the second horizontal transfer path are disposed in the vicinity of one end of the vertical transfer unit. The imaging device according to any one of claims 1 to 3,
The imaging device according to claim 1, wherein the predetermined driving method is a three-phase driving method or a four-phase driving method. An imaging apparatus comprising the imaging device according to any one of claims 1 to 4,
Adding means for adding the signal charges accumulated in the plurality of pixels of the same color by transferring the signal charges in the forward and reverse directions in the second horizontal transfer path;
Control means for activating the adding means when performing live view display relating to the subject based on image signals sequentially output from the image sensor, or when performing moving image photographing relating to the subject based on the image signal; ,
An imaging apparatus comprising:

Images